Various designs of dispensing assemblies of this kind are known in the art, e.g. from WO-2007/098624 to the applicant of the present invention where a syringe holder is adapted to receive two separate storage containers and e.g. a mixer is attachable thereto, the pistons of the storage containers being moved forward by plungers. This device is appropriate for many applications but not for the use of conventional syringes that are to be dispensed jointly with a high mixing accuracy. US-2007/005020 discloses a double syringe comprising three distinct interconnected portions that allow jointly dispensing the syringes. In this simple construction, however, the guidance of the syringe plungers is not precise. This is also true for US-2006/116646 as well as WO-2008/001221.